The ratio of luminance between the brightest white in a display system to the darkest black that can be produced is called the contrast ratio. In a micromirror based display system, higher contrast ratios can be achieved when there is a larger difference in angle between light reflected from the mirrors in their ON state and light reflected from the mirror in the OFF state. One way to increase the difference in reflected angles is by having the micromirrors be electrostatically deflected in opposite directions (to ON and OFF states) from a non-deflected state.
Micromirror based display systems that have only a single addressing electrode per micromirror often deflect the micromirror to an ON state, but leave the micromirror undeflected in the OFF state (or deflect minimally the micromirror in the OFF state). This results in a decrease in the difference in angle of the light reflected in the ON state vs. the OFF state, thus decreasing contrast ratio. Therefore, what is needed for such single addressing electrode systems, is higher contrast ratio.